He has starred in many movies and had supporting roles in dozens more. He has performed in movies filmed in many languages, including Swedish, Norwegian, English, Italian, German, Danish, French and Spanish.

Some of his most memorable film roles include knight Antonius Block in Ingmar Bergman's The Seventh Seal, Jesus in The Greatest Story Ever Told, Father Merrin in The Exorcist, Joubert in Three Days of the Condor, The Three Eyed Raven in Game of Thrones, and Ming the Merciless in the 1980 version of Flash Gordon.